With the development of various information communication technologies, mobile electronic device have been increasingly deployed. These electronic devices receive and transmit data to and from other external electronic devices through communication networks, thus providing the user with mobile data communication services.
Under the recent trend of the digital convergence, various types of mobile devices have been developed. For example, one type of device called the smartphone supports various functions such as connecting to the Internet, voice calling, health monitoring, media playback, image and video capture via a camera, etc.
Due to this multitude of functions, smartphones are generally usually carried by the user and are often used throughout the day. For this reason, the battery life of the electronic device becomes an important issue. When the user is concerned that battery power may be depleted while the user is mobile, he or she may carry a charging device such as a portable charger along with the electronic device. This may be inconvenient to the user.